Correlation of overlapping magnetic measurement data from multiple magnetic navigation devices and update of the geomagnetic map based on this data

Abstract

In one embodiment, a method includes receiving magnetic measurements of one or more geographical regions collected over a period of time from a plurality of magnetic navigation devices, performing a similarity correlation analysis on the magnetic measurements, generating one or more geographical map patches corresponding to the one or more geographical regions based on the similarity correlation analysis, transmitting the one or more geographical map patches to a main mapping server for updating the geomagnetic map data, receiving the updated geomagnetic map data from the main mapping server, and transmitting the updated geomagnetic map data to one or more of the magnetic navigation devices for navigation and location determination.

Description

Technical Field

[0001] The present disclosure generally relates to magnetic mapping and navigation.

Background Art

[0002] Navigation systems are provided in a variety of different architectures for use in different applications, including personal, commercial, and military. Many such systems operate on the premise of a Global Navigation Satellite System (GNSS). GNSS is a general term used to describe a network of satellites that can be used to create a dataset of Position, Navigation, and Time (PNT). The Global Positioning System (GPS) is a widely used form of GNSS. Also, the regional application of such systems is also used to generate more specific PNT data for each region. For example, Galileo can be used in Europe, GLONASS can be used in Russia, and the BeiDou Navigation Satellite System (BDS) can be used in China.

Summary of the Invention

Problems to be Solved by the Invention

[0003] GNSS may have points of deficiency. For example, some GNSS lose reliability when operating inside a building or area where network communication to the device is intermittent. Some GNSS lose reliability when operating in a dense urban environment where large buildings are interfering with communication signals. Some GNSS lose reliability when operating in areas such as caves, tunnels, and mountains that obstruct the reception of signals from GNSS satellites by the positioning device. Further, some GNSS are vulnerable to malicious attacks by electronic or physical interference that degrades their reliability.

Brief Description of the Drawings

[0004]

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[0005] In certain embodiments, magnetic measurements are used to perform location determination or navigation based on geomagnetic map information. In certain embodiments, location determination or mapping is performed based solely on magnetic measurements. In certain embodiments, location determination or mapping is performed based on a combination of magnetic measurements and additional location information including, but not limited to, GNSS data or measurements created by an inertial measurement unit. In certain embodiments, magnetic measurements created by a magnetic navigation device are used to create and continuously update geomagnetic map information. In this way, an accurate geomagnetic map that is updated in response to changes in the environment can be made available within the magnetic navigation system.

[0006] GNSS can be effective in providing navigation data, including maps and directions for navigation, for various applications. However, GNSS is not without drawbacks and is susceptible to reliability issues when there are interferences in the signals used to perform location identification, for example, when there are local anomalies such as buildings or other geographical terrains. Furthermore, GNSS-based navigation systems can be vulnerable to attacks from malicious actors, which may result in a complete loss of functionality or lead to false location identification results.

[0007] When there are problems with the reliability of GNSS, navigation data is often obtained by a set of secondary devices such as an inertial navigation system (INS). INS uses a combination of mechanical systems or electromechanical systems to calculate the position, orientation, and velocity of a moving object. For example, some systems can calculate the position, azimuth, and velocity of a navigation device by dead reckoning using a computer system, motion sensors, and rotation sensors. This can be done without relying on external references such as GNSS. However, if the inertial system is not periodically corrected using accurate position data, it accumulates navigation errors that may result in inaccurate data.

[0008] To determine a location, the Earth's geomagnetic field (GMF) can be utilized. The Earth's GMF is unique for each region and can depend on many factors including magnetic anomalies, artificial electromagnetic fields, or seasonal or diurnal variations. The obstacle to using local GMF information to perform location determination or navigation is that a high-resolution GMF map cannot be utilized globally. In fact, currently existing maps based on the GMF can typically only provide what is known as a resolution of 2 arc minutes. This is equivalent to a measurement with a resolution of approximately 3.6 km and can be difficult to use for accurate location determination and navigation purposes, especially at close distances such as in an urban environment. Thus, a magnetic navigation system in certain embodiments can perform location determination with sufficient accuracy to improve location determination or navigation that can be performed using only GNSS and in combination with GNSS and other sensing modalities including, but not limited to, an inertial measurement unit, by constructing a geomagnetic map with sufficient resolution using measurements obtained via various different magnetic navigation devices.

[0009] Turning now to the drawings, there are shown navigation systems and methods for performing location identification or navigation in certain embodiments by using magnetic map data in combination with GNSS data. In certain embodiments, the reliability of the navigation system can be enhanced by using magnetic measurements to obtain location identification information from a magnetic map in combination with location identification information from GNSS, or additional functionality can be performed, including but not limited to reliable indoor navigation or reliable navigation in an environment where a navigation device may be at least partially blocked from GNSS satellites (e.g., a dense urban environment). In certain embodiments, the navigation system can utilize a main mapping server designed to maintain a current geomagnetic map in at least a portion of the earth where the geomagnetic map can include information from the current geomagnetic field (GMF) as well as information obtained from a magnetic navigation device. Also, in certain embodiments, the navigation system can incorporate a regional data server (also interchangeably referred to herein as a regional magnetic data service, a regional mapping server, a regional navigation server, or a regional server) that communicates with the main mapping server and provides magnetic mapping data collected based on measurements made by a magnetic navigation device. In certain embodiments, the magnetic mapping data provided by the regional mapping server may be in the form of a patch data set. The particular data transferred depends largely on the magnetic measurement capabilities of the magnetic navigation device, the processing performed by the regional server, or the requirements of a particular navigation application. In some embodiments, the main navigation or mapping server can create a magnetic map (composed of various layers of magnetic and other data) using data received from the regional navigation server, update an existing geomagnetic map, and improve the geomagnetic map based on the received data (e.g., magnetic navigation device measurement data or data derived from magnetic navigation device measurement data including but not limited to a geomagnetic map patch data set).In certain embodiments, the regional server receives data from individual magnetic navigation devices located within a specific area.

[0010] In certain embodiments, the data set from the device can carry various information including (but not limited to) information within the area and local magnetic anomaly data. The regional data server can continuously update and improve the local geomagnetic map data or geomagnetic map patch data set by processing the data received from the magnetic navigation device. In certain embodiments, the regional server can apply a weight to each data set received from the magnetic navigation device based on factors including (but not limited to) the reliability and accuracy of the position identification (GNSS) data reported by the hardware used and the magnetic navigation device. In certain embodiments, the regional data server can generate an updated geomagnetic map patch data set (or patch data set) based on the data received from the magnetic navigation device over a period of time. In certain embodiments, the updated patch data set can be generated based on a comparison with similar probability data, and thus can provide an improved and refined data set for updating the geomagnetic map data utilized by the magnetic navigation system. The specific method of the server for determining the geomagnetic map or the method for updating the geomagnetic map depends largely on the requirements of a specific navigation application.

[0011] In certain embodiments, the navigation system can continuously generate updated geomagnetic mapping data for use by a magnetic navigation device that performs positioning or navigation. Such a system can provide reliable geomagnetic mapping data based on a relatively stable GMF and can also improve the resolution of data based on magnetic measurements obtained by individual navigation devices. In this way, the navigation system in certain embodiments can provide reliable geomagnetic map information compared to conventional navigation systems that rely only on GNSS, and can also provide a more reliable positioning and mapping service by utilizing this information. Further, as the number of magnetic navigation devices that acquire magnetic field measurements and transmit new information to the system's server increases, the geomagnetic map can be periodically updated with increasingly accurate information.

[0012] A magnetic navigation system, a method for performing positioning or navigation based on magnetic measurement values using a geomagnetic map, and a magnetic navigation device in a specific embodiment will be further described below. FIG. 1A shows an exemplary magnetic navigation system in which a magnetic navigation device utilizes geomagnetic map information to perform positioning or navigation. In this system, the geomagnetic map information is updated based on magnetic measurement values created by the magnetic navigation device. In a specific embodiment, the magnetic navigation system 100 can provide positioning or navigation services within one or more geographical regions (102-108). At any given time, various magnetic navigation devices (110) can be present within each region (102-108). Examples of the magnetic navigation device 110 include a mobile phone, a vehicle navigation system, a UAV navigation system, or any other device capable of receiving geomagnetic map information, capturing magnetic measurement values, or transmitting information based on magnetic measurement values (but not limited thereto). The characteristics of the magnetic navigation device are limited only by the requirements of a specific application.

[0013] Many magnetic navigation devices can communicate with various servers, including (but not limited to) servers within a magnetic navigation system, via a communication network of cellular data or satellite data. Much of the following description refers to magnetic navigation devices that have a network connection and retrieve data from a remote server, but magnetic navigation devices in certain embodiments store geomagnetic map information or additional map information necessary to render a UI in the memory on the magnetic navigation device and can perform location identification or navigation in the absence of a network connection. When a network connection is available, magnetic navigation devices in certain embodiments can receive data, including (but not limited to) geomagnetic map information, UI map information (e.g., map tiles that can be displayed within a location or mapping UI), or navigation information (e.g., route information, or instructions for each route change), via the network connection. In certain embodiments, a single server system provides the geomagnetic map information in combination with other map information. For example, the geomagnetic map information can be provided as a layer of map information that includes (but is not limited to) visual map information that can be displayed within the UI. In certain embodiments, the geomagnetic map information is obtained by the server from different servers that provide the UI map information or the navigation information. In certain embodiments, the magnetic navigation device accesses mapping or navigation information via an integrated interface, and specific information is retrieved from various servers or database systems within the magnetic navigation system and provided to the magnetic navigation device via the integrated interface. Specific server architectures available in a magnetic navigation system in certain embodiments are further described below with reference to the regional server system 112 and the main server system 116 shown in FIG. 1A. Many other server architectures can be utilized within the magnetic navigation system according to the requirements of a particular application in certain embodiments.

[0014] In certain embodiments, the magnetic navigation system incorporates one or more regional server systems 112 that can communicate with magnetic navigation devices that communicate via a particular network or within a particular geographic region. The regional server system can transmit geomagnetic map data 114 to magnetic navigation devices 110 within a geographic region (102-108) and can also receive magnetic measurement information. As described above, the regional server system 112 can also transmit other types of information, including but not limited to, UI map information or navigation information.

[0015] In certain embodiments, the magnetic navigation device 110 can continuously provide magnetic measurement information to the magnetic navigation system 100 (e.g., to the regional server system 112 or the main server system 116). In certain embodiments, the magnetic navigation device 110 periodically provides a data log of magnetic measurement information. In certain embodiments, the magnetic navigation device 110 reports magnetic measurement values based on a network connection. For example, the magnetic navigation device 110 can wait until it is connected to a broadband internet connection (e.g., via a WIFI access point) and can upload a magnetic measurement data log to a server system (112 or 116) within the magnetic navigation system 100. The particular method of exchanging data between the magnetic navigation device and a server within the magnetic navigation system depends largely on the requirements of a particular application.

[0016] FIG. 1B shows an exemplary magnetic navigation device. The magnetic navigation device 150 includes a processing system 152 that communicates with a memory 154, and the memory 154 includes a magnetic navigation application 155. This processing system can be implemented using a general-purpose microprocessor, a microcontroller, a digital signal processor, a graphics processing unit, or any combination of application-specific or software-controlled devices capable of performing logical or computational operations. In certain embodiments, the memory 154 includes a non-volatile memory system. In certain embodiments, the magnetic navigation application 155 is temporarily downloaded and stored in the memory 154. In certain embodiments, the memory 154 can also be used to store additional data including, but not limited to, geomagnetic map information, UI map information (e.g., map tile image files), or navigation information. As described above, the magnetic navigation device in certain embodiments can store map information locally to enable magnetic navigation even when there is no network connection.

[0017] The processing system 152 also communicates with the magnetic sensor system 156. Also, in the illustrated embodiment, the magnetic navigation device also includes a GNSS receiver 158, an inertial measurement unit (IMU) 160, and a wireless communication module 162 that communicates with the processor 152. In certain embodiments, the GNSS receiver 158, IMU 160, or wireless communication module 162 can be utilized to obtain position information available to the magnetic navigation application 155 in combination with or as an alternative to position information derived from magnetic measurements obtained using the magnetic sensor system 156. Also, in certain embodiments, the wireless communication module 162 can be utilized to obtain supplementary position information. Also, the wireless communication module 162 can be utilized to communicate with a server system within the magnetic navigation system to obtain geomagnetic map information or to transmit data related to magnetic measurements. Although various magnetic navigation device architectures have been described above with reference to FIG. 1B, any of a variety of architectures (including, but not limited to) can be utilized in which the GNSS receiver or wireless communication module performs the above-described functions due to a separate processor or memory (thus eliminating the need for a separate processing system or memory component). Thus, depending on the requirements of a particular application in a particular embodiment, many different magnetic navigation device implementations can be utilized that include fewer or additional components than the components shown in FIG. 1B.

[0018] Referring again to FIG. 1A, in certain embodiments, the regional data server 112 can be configured to store the transmitted magnetic measurement information 114 received from the magnetic navigation device 110. The stored magnetic measurement data can be used to generate updated geomagnetic map information for a particular region. The regional data server 112 can then transmit an update to the geomagnetic map (e.g., an updated geomagnetic map patch) to a main server system or a plurality of server systems located within geographically distinct data centers, and this server system can utilize the update to the geomagnetic map to perform an update to the global geomagnetic map. The particular method by which magnetic measurements supplied from a plurality of magnetic navigation devices can be utilized within a single server system or a hierarchy of server systems to update a regional or global geomagnetic map depends largely on the requirements of a particular application in a particular embodiment. The process for collecting magnetic measurements and updating the geomagnetic map in a particular embodiment is further described below.

[0019] In certain embodiments, the magnetic navigation system can "patch" or improve the global geomagnetic field (GMF) global geomagnetic map. For example, a magnetic navigation server (e.g., main server system 116) can maintain a geomagnetic map that can be a dual-redundant "master map" of the Earth's GMF so that the service does not interrupt if the master file is damaged. The master geomagnetic map can serve as a baseline for establishing a higher-resolution geomagnetic map that can be used for detailed magnetic navigation. In certain embodiments, for example, the master geomagnetic map stored in one or all of the main servers of the magnetic navigation system can be based on data received from the EMAG2 (Earth Magnetic Anomaly Grid with a resolution of 2 arc-minutes) data model. Additionally, the master geomagnetic map may include a rough gradient map of the GMF and additional data layers including other information such as magnetic susceptibility and conductivity. In certain embodiments, various layers of additional data can be updated periodically or in real-time when information is generated from the magnetic navigation device and supplied to the regional server. Similarly, the master geomagnetic map can be updated or improved to have a higher resolution than the baseline EMAG2 model in certain embodiments. Thus, the master geomagnetic map, when updated, can be used for improved location identification or navigation.

[0020] In certain embodiments, magnetic mapping data can be provided in a plurality of layers of two-dimensional data based on the height of the magnetic device. For example, one device may be in an aircraft, another device may be near the ground, and still another device may be located at different heights within a building. Thus, various embodiments of system programming can extrapolate the two-dimensional data set to render a three-dimensional data set to generate a more refined three-dimensional map of the magnetic anomalies. Thus, the three-dimensional data set can be stored in the main server. Similarly, some embodiments can utilize the three-dimensional data set for location identification.

[0021] Updating the geomagnetic map in certain embodiments involves capturing magnetic measurement information using an active magnetic navigation device within a magnetic navigation system. In certain embodiments, the magnetic measurement information is generated by the magnetic navigation device and can be stored or provided to the magnetic navigation system in several different formats including, but not limited to, decimal data, TINYINT (tiny integer), or integer data format. Similarly, the values of the data can be provided in degrees (e.g., representing latitude and longitude values), and any number of numerical types such as metric or imperial measurements representing respective resolution or cell size. By using such combinations of values, it should be understood that a magnetic information capture trajectory (sometimes simply referred to as a trajectory) can be generated for each individual magnetic navigation device that is operable within or for use within the magnetic navigation system to capture magnetic measurement information. In some embodiments, trajectories can be provided to the magnetic navigation system by magnetic navigation devices using various different data formats or values. For example, Table 1 below shows trajectory data generated in certain embodiments.

[0022] [Table 1]

[0023] The structure of the trajectory data can be implemented in the manner detailed below. That is, TRAJECTORY: An array of elements of type "POINT". POINT: { double lat; double Ion; float height; float heading; / / Magnetic azimuth time_t timestamp; / / Timestamp of the current measurement; double accelerometerX; double accelerometerY; double accelerometerZ; double mag_x; double mag_y; double mag_z; double suscept; double conductivity; float v_accuracy; / / GNSS vertical accuracy (m); -1 if unavailable float h_accuracy; / / GNSS horizontal accuracy (m) -1 if unavailable short mode; / / 0 - regular mode; 1 - GNSS-denied mode; 2 - Network-denied mode; 3 -hblind mode };

[0024] Depending on the requirements of a particular application in a particular embodiment, any of a variety of data structures can be utilized to report magnetic measurement values.

[0025] In certain embodiments, baseline magnetic mapping can be updated that includes data parsed from the EMAG2 dataset using magnetic measurement information directly reported by a magnetic navigation device or magnetic measurement information included in a trajectory reported by a magnetic navigation device. The data of EMAG2 can be used as a baseline for determining a level of resolution that may be necessary to improve the functionality of the entire magnetic mapping system. For example, the achievable level of resolution improvement can be determined by the positioning accuracy of GNSS device data and the update rate of the magnetic sensors inherent to each device within the system.

[0026] In certain embodiments, the key-related data can include (but is not limited to) magnetic data related to latitude, longitude, altitude (height), and device type. The general layer data can include, in certain embodiments, various values or data sets related to the geographical location of the device. This can be extremely useful in determining the types of magnetic anomalies that are already known and can be described in terms of overall resolution improvement. Further, data on magnetic susceptibility and conductivity can be generated by devices within the area. Such data can be used to establish various confidence factors associated with each device. The confidence factor can, in certain embodiments, help determine the level of accuracy of the data provided and can also act as a weighting factor used to determine the trajectory data of the device.

[0027] As described above with respect to FIG. 1A, the regional server can be used to preprocess magnetic measurement information provided by a magnetic navigation device. In certain embodiments, the magnetic navigation system can utilize the regional server to generate an update for a region or a “patch” of data for the geomagnetic map. The update can be implemented using, as an additional data layer, or as any of various data structures that reflect modifications to the underlying geomagnetic map information. In certain embodiments, the regional server can create a geomagnetic map patch for the master geomagnetic map based on trajectories that can generally be classified by device type and device hardware. For example, the magnetic navigation system can weight the reliability of information (e.g., magnetic measurements by a cellular phone versus magnetic measurements by a vehicle-mounted magnetic navigation device) based on factors including, but not limited to, the sensitivity or reliability of the magnetometer utilized by the magnetic device, or the reliability of other positioning information generated by the magnetic navigation device. Trajectories of different devices can be collected by various regional servers 112, and by processing the magnetic measurement information included in the trajectories by the regional server, a geomagnetic map patch can be created for use in updating the geomagnetic map. To update the geomagnetic map, the geomagnetic map patch can be transmitted to the main server system.

[0028] Much of the above discussion relates to the use of trajectories to provide magnetic measurement information for the purpose of updating the geomagnetic map, but the method based on the transmission of trajectory data is simply a useful implementation form because it does not depend on the need for continuous transmission of magnetic measurement information by a magnetic navigation device. Thus, by using trajectories, it can be made possible for a magnetic navigation system to aggregate magnetic navigation data at an advantageous time (e.g., when a low-cost / high-speed network connection can be utilized by the magnetic navigation device). Accordingly, depending on the requirements of a particular application in a particular embodiment, magnetic measurement information can be provided using any one of a variety of different data structures or at any one of a variety of communication frequencies.

[0029] Figure 2 is an exemplary sequence diagram of an exemplary magnetic navigation system conceptually showing communication between a magnetic navigation device and a server system in a particular embodiment. In a particular embodiment, the magnetic navigation device 202 can be configured to communicate wirelessly with a regional server 204. In a particular embodiment, the magnetic navigation device 202 can transmit magnetic map information 206 generated from the device to the regional server 204. The regional server 204 can perform several operations described below to analyze and process incoming data from the magnetic navigation device to generate an update to the geomagnetic map. In the illustrated embodiment, a geomagnetic map patch data set 208 that can be transmitted to the main server 210 used to update the earth geomagnetic map is generated using magnetic measurement information received from the magnetic navigation device. As described above, the update to the earth geomagnetic map can take the form of an additional information layer within the earth geomagnetic map. In a particular embodiment, the main server 210 can transmit updated geomagnetic map data 212 to the regional server for storage and supply to the magnetic navigation device. Next, when the magnetic navigation device 202 requests geomagnetic map data to perform navigation (214), an updated geomagnetic map file 216 can be provided by the server 204, and this file can be utilized by the magnetic navigation device to perform location identification or navigation. The geomagnetic map information can be region-specific. Thus, the magnetic navigation device 202 does not need to request the entire earth geomagnetic map, but instead can request cubes or tiles of the geomagnetic map for a specific region. For example, many magnetic devices may have various degrees of uncertainty that may require two-dimensional or three-dimensional data for location identification / navigation. When a magnetic device is placed on or under a bridge, three-dimensional GMF information can be provided within a cube to enable navigation.As another example, there can be vehicles on the road that provide tiles and require no data other than two-dimensional data for positioning. In certain embodiments, the magnetic navigation device can download UI map tiles 216 so that the magnetic navigation device can display an appropriate UI as it continues along a trajectory.

[0030] FIG. 3 shows an exemplary method for generating exemplary magnetic mapping data. In certain embodiments, a magnetic navigation device captures magnetic measurements (302) using a magnetometer present on the device. The measurements made by the magnetic navigation device are unique to the magnetic navigation device in that they depend on the position of the magnetic navigation device and the particular magnetometer used by the magnetic navigation device. In certain embodiments, each magnetic measurement made by the magnetic navigation device includes three components of magnetic field strength (but is not limited to these) measured along with position and orientation data from a GNSS / INS or any reliable navigation system. In certain embodiments, the position information can be supplemented with additional position data including (but not limited to) position information derived from measurements within a digital communication system or IMU measurements. In certain embodiments, the magnetic measurements, along with navigation log data and information including (but not limited to) the magnetic navigation device type, sensor type, or accuracy of the position information, are transmitted and stored by a navigation system (e.g., within a regional server) for use in calculating updates to the geomagnetic map. In certain embodiments, the magnetic measurement information can be represented by Equation (1) below. That is,

Number

[0031] In a particular embodiment, the magnetic measurement information generated by a particular magnetic navigation device can include various different elements, such as information identifying the device hardware used to capture the measurement values as described above, and the reliability of the hardware. Additionally, region-device-specific data can take into account other variables such as local anomalies (but not limited to) that affect the regional magnetic field. An anomaly can be any number of objects that can provide information about the local magnetic field, such as buildings, bridges, tunnels, cell towers, lampposts, any number of artifacts, or any geographical features that can be specific to the region.

[0032] The magnetic measurement information generated by a particular magnetic navigation device can be transmitted to a regional server for further processing 304. The regional server can generate a regional trajectory 306 based on the region-device-specific data. Alternatively, the magnetic navigation device can provide the magnetic measurement information as a trajectory. In a particular embodiment, the magnetic measurement values can then be used to generate a regional geomagnetic map patch 308, which can be transmitted to the main server system 310. The main server can use the geomagnetic map patch to update the global geomagnetic map 312 with the patches received from the regional server. As described above, these updates can be reflected as an additional layer of the global geomagnetic map maintained by the main server system.

[0033] Regarding magnetic measurement values or local anomaly data that can be collected by various regional devices, such data can be assigned to different reliability or confidence levels for each use in the overall calculation of geomagnetic map patch data. The reliability or confidence level may also be referred to as a probability layer in various embodiments, and also includes the number of magnetic navigation devices that reported an anomaly, the reproducibility of measurements across different magnetic navigation devices, the accuracy and type of magnetometers used to collect the magnetic measurement values, whether the magnetometer is recognized by the device, the type of movement, or the reliability of position determination (GNSS data), as well as seasonal variations that may affect the local magnetic field. Further, the probability layer can include other types of information such as information describing known local anomalies including (but not limited to) materials present in the known local anomalies. The materials can potentially have various effects on the characteristics of the local magnetic field. Local anomalies such as buildings, bridges, roads, etc. can be made of any number of materials. Further, such anomalies and their respective materials can be related to information on the relative magnetic susceptibility and conductivity that can be understood by the device. Thus, a database containing known magnetic properties of various types of materials can be established or utilized so that corrections can be made to the magnetometer and / or included in the corresponding calculations to generate geomagnetic map patches used when updating the Earth's geomagnetic map. In certain embodiments, this data can be filtered into various types of probability layers such as data on the magnetic susceptibility and conductivity of the device. In various embodiments, the probability layer can include, but is not limited to, layers of coordinates of the device or object, value vectors of the local magnetic field, gradient vectors of the local magnetic field, values of magnetic susceptibility, values of conductivity, and magnetic navigation device types.

[0034] In certain embodiments, the geomagnetic map is created using measurements from various magnetic navigation devices, including measurements created via a more accurate measurement platform for the sensors and measurements created using less expensive sensors. For example, some magnetic navigation devices may include GNSS and INS solutions, Novatel's Synchronized Position Attitude and Navigation (SPAN) technology (such as PwrPak7-E1). These magnetic navigation devices may be able to provide time, position, velocity, and attitude parameters. In certain embodiments, magnetic measurements obtained by a magnetic navigation device with a more reliable magnetic measurement platform are given a higher level of confidence (or reliability) within the probability layer utilized to determine updates to the Earth's geomagnetic map. Conversely, a lower level of confidence may be given to magnetic navigation devices with less accurate components and technology. Components with lower accuracy, such as magnetometers within a mobile device, may be relatively reliable for location and navigation despite the level of noise that may be generated by some of these less accurate sensors.

[0035] In certain embodiments, a magnetic navigation system can construct a high-reliability and high-precision geomagnetic map with improved resolution by utilizing more magnetic measurements captured using less accurate magnetic sensors or location techniques. For example, since similar sensors tend to generate the same or similar errors that make the geomagnetic map very predictable, many embodiments can utilize the errors or noise often generated from less accurate sensors. Thus, sensor data containing errors can be used to generate rough mapping data and to perform location identification on a rough scale, where "rough" includes data containing known errors or noise. Collecting many magnetic measurements from the same or similar types of noisy sensors representing a rough map can be useful in developing patches for the Earth's geomagnetic map by utilizing methods including, but not limited to, quantization of the GMF gradient values. Much of the above discussion relates to collecting magnetic measurements using a magnetic navigation device, but in certain embodiments, a magnetic navigation system can also receive magnetic measurements from a dedicated magnetic measurement device incorporating very accurate geographic location and magnetic field measurement techniques. In this way, the magnetic navigation system can continuously improve the geomagnetic map information available to the magnetic navigation device by periodically capturing very accurate magnetic measurements within a specific area. Thus, references herein to obtaining magnetic measurements using a magnetic navigation device are to be understood as encompassing obtaining measurements using a dedicated magnetic measurement device that also forms part of the magnetic navigation system. To collect magnetic measurements and process the magnetic measurement information to generate reliable geomagnetic map information for location identification or navigation according to the requirements of a specific application in certain embodiments, any of a variety of strategies can be employed.

[0036] In certain embodiments, a method for updating a global geomagnetic map can follow a systematic process of obtaining magnetic measurement information from magnetic navigation devices within a region and then assigning the magnetic measurement information to probability layers for processing. Further, the probability layers can be compared for similarity in the magnetic measurement information in order to generate a superposition of magnetic measurement information useful for generating an updated geomagnetic map patch. Magnetic measurements similar to those described above can be stored and accumulated in a (distributed) database for use in generating updates to the global geomagnetic map. In certain embodiments, the probability layers or magnetic measurement data sets can be compared over time. In other words, magnetic measurements over time in a region can be compared to establish a reliable data set useful for generating updates to the global geomagnetic map. Magnetic measurements taking into account changes in the data over time can be represented by Equation (2) below. That is, [Number] where the three-dimensional components of the GMF are measured over the time intervals t1...tN. The magnetic measurements (successive readings of the magnetometer) depend on the movement of the object, which is characterized by the three linear velocity components Δx, Δy, Δz, the three angular velocity components Δγ, Δθ, Δψ, and the update rate Δt = Δt i -Δt i-1 of the sensor system used to capture the magnetic measurements.

[0037] Figure 4A is an exemplary time overlay of various exemplary magnetic profiles in an exemplary region, conceptually showing the capture of magnetic measurements over different time intervals in a given region. During the first time interval 402, two magnetic navigation devices capture magnetic measurements while traversing two different paths within the same region of the GMF. Within the second and third time intervals (404 and 406), additional magnetic navigation devices capture magnetic measurements while moving through this region. Magnetic measurements created at different times within a cell 408 of a region are shown. Given the uncertainty in the position or trajectory of the magnetic navigation device, subsequent processing of the magnetic measurements can take into account the uncertainty in both the magnetic measurements and the position of the magnetic navigation device at the time the magnetic measurements were generated. For processing purposes, each magnetic measurement can be assigned to a corresponding resolution cell within the region (e.g., the cell most likely containing the position of the magnetic navigation device at the time the magnetic measurement was created). The GMF within the corresponding cell can be a function of 3D coordinates similar to that shown in Equation (2) above. The 3D coordinates can be represented by Equation (3). That is,

Number

Number

[0038] In certain embodiments, by using techniques such as Gaussian process regression (GPR), but not limited thereto, equations (3) and (4) above can be convolved to include the change in time Δt associated with the probabilistic estimates of coordinates, velocities, and orientations during mapping. In some embodiments, the magnetic measurements collected by various magnetic navigation devices within the region can be aligned to the same time interval and compared using approximate coordinates. In certain embodiments, this is performed in a way that takes into account potential errors or noise that could be generated from any given device. Thus, the navigation system in certain embodiments can utilize the collected magnetic measurement information to determine the magnetic field gradient using the matrix given by equation (5) below. That is, [Number]

[0039] Furthermore, by interpolating the mapping data and predicting Δx, Δy, Δz, the magnetic measurements can be transitioned from previous measurements to new measurements. When multiple magnetic measurements captured by different magnetic navigation devices are available within the region, an analysis can be performed to evaluate the similarity between the magnetic measurements by using correlation analysis, but not limited thereto. Thus, the navigation system in certain embodiments can utilize the similarity between the magnetic measurements to construct a probabilistic magnetic gradient map or a geomagnetic map patch used to update the geomagnetic map. The probabilistic magnetic field maps according to many embodiments can improve the resolution by combining information from a global reference database and gradient vector (3-axis) geomagnetic map data. In certain embodiments, an analysis such as similarity correlation analysis, but not limited thereto, can be repeated over time to update the probabilistic magnetic gradient map. The correlation of similarity in magnetic measurements is in stark contrast to typical GPS / GNSS techniques that seek differences in measurements to improve accuracy.

[0040] For example, FIGS. 4B and 4C show an exemplary comparison of exemplary quantization trajectory data between, for example, a sensor and mapping data, showing an example of gradient magnetic mapping data of a sensor with known errors (FIG. 4B) compared to similar values (FIG. 4C) that can be stored in a map. In FIG. 4B, graph 414 shows raw data from the sensor and graph 418 shows the corresponding quantized data. Similarly, in FIG. 4C, graph 416 shows raw data regarding the GMF gradient extracted from the map along the linear coordinate X (meters), and graph 420 includes the same but quantized data. The quantized data can be divided into different quantization levels 412, as indicated by the horizontal lines in graphs 418 and 420, for example. By using the quantization levels 412, the quantized trajectories for each sensor 414 and map 416 can be shown. Since the shape is retained, it can be seen that the gradient profile 410b extracted from graph 416 is different from the gradient profile 410a from the sensor 414 for each scale. The correspondence between the gradient profiles 410a and 410b can be detected, and thus reliable navigation can be provided. Conventional systems can be computed by using an error measurement criterion that compares the absolute value difference or the squared difference in the quantized trajectory data, but this cannot provide a consistent data set for generating improved magnetic mapping data. In contrast, many embodiments compute to compare the trajectory data with respect to similarity rather than difference. In some cases, the error metric can be limited to 1 (100%), providing the results of the comparison data much faster and with much higher accuracy than conventional difference methods.

[0041] Figures 4D - 4I show exemplary trajectory data compared for improved functional similarity, showing how some embodiments can use the similarity of trajectory data for location - determination purposes. Figure 4D shows, for example, a simulated scalar magnetic field map, where various magnetic anomalies 420 are represented by peaks and valleys in the "Z" direction of the map. Similarly, Figure 4E shows a 2 - D magnetic anomaly map that is the same 100×100 square, showing the intensity of each of the various anomalies. By using the data from each magnetic map, various embodiments can generate gradient - mapping data for each region, as shown in Figure 4F. At the same time, the trajectory for any given magnetic device can be generated based on the numerous methods and embodiments shown above. An example of the magnetic trajectory and its gradient of an object within the region can be shown by the graph of Figure 4G. Subsequently, many embodiments can overlay and compare the trajectory data measured by the magnetic device (Figure 4G) with the map data (Figures 4D - 4F), and this comparison can be shown in Figures 4H and 4I, where the value of the normalized cross - correlation coefficient (NCC) is shown as the result of comparing a known trajectory with a set of other trajectories from the map data (Figures 4D - 4F). By comparing the similarity between the data, the most likely trajectory of the movement can be found. In such an example, the most likely trajectory can be shown by the fifth column, where the NCC value is 0.9978, which is the highest in comparison with others. From Figures 4H - 4I, it can be seen that to obtain the correct value regarding the column number, it was sufficient to compare only the first 24 points out of all the trajectories (95 points).

[0042] In certain embodiments, if the similarity correlation method does not produce the desired level of accuracy within the region, other correlation methods can be used to improve the accuracy. For example, some embodiments can use a correlation reference function based on the calculation of the cross-correlation function of a random process. In certain embodiments, a magnetic navigation system can use a differential reference function that can be commonly presented in this field. In certain embodiments, a spectral reference function can be used to perform correlation in the spectral domain. In certain embodiments, depending on the requirements of a particular application in a particular embodiment, any of a variety of functions can be utilized to obtain geomagnetic map information using magnetic measurements created by various magnetic navigation devices.

[0043] Referring now to FIGS. 5-7, a magnetic mapping dataset in a particular embodiment can be shown. FIG. 5 shows exemplary latitude and longitude trajectory data captured while traversing the same or nearly similar paths within a given area on different days. It can be shown that improved geomagnetic map information can be generated by using the overlapping data shown along the centerline of the curve. In various embodiments, the geomagnetic map data can continue to be improved with an increasing number of magnetic measurements from various magnetic navigation devices within the area. The different datasets shown in FIG. 5 appear to be somewhat offset from each other, but the datasets represent the same path over two different periods. Conditions can vary from day to day, and local anomalies affecting each dataset can also vary. However, as described above, overlapping datasets can be compared for similarity, and by applying appropriately determined weighting factors to the datasets, greater consistency can be established. The magnetic measurements shown in FIG. 5 are also shown in the chart shown in FIG. 6. In particular, FIG. 6 shows how the magnetic field changed for each trajectory shown in FIG. 5, by date (corresponding to gray and black), according to latitude (shown by reference numeral 602) and longitude (shown by reference numeral 604). Also, each dataset shows a slight offset but is comparable.

[0044] FIG. 7 shows an exemplary regional geomagnetic map formed based on magnetic measurements captured by several different magnetic navigation devices. The geomagnetic map shows the corresponding intensities at the respective latitude and longitude positions of the map. The greater the number of magnetic navigation devices collecting reliable magnetic measurement information, the greater the amount of overlapping data available for generating a high-resolution geomagnetic map of each region. In certain embodiments, by implementing the methods and systems described above, a magnetic navigation system can compile device-specific data from magnetic navigation devices and also compare similar data, thus creating a geomagnetic map layer that can use similar data to generate improved-resolution geomagnetic data specific to a particular class of devices. The particular methods by which a magnetic navigation system processes magnetic measurements obtained from different classes of magnetic navigation devices to obtain updated geomagnetic map information depend largely on the requirements of a particular application.

[0045] Turning now to FIG. 8, a magnetic navigation system 800 is shown. In certain embodiments, a particular area 802 may have several magnetic navigation devices, or objects such as metal objects, automobiles, high power lines, subways, etc. (804-814). Each magnetic navigation device (804-808) can transmit magnetic measurement information to a regional server 818, and the magnetic measurement information may include device profile information 816. The individual magnetic measurement values may include information about various objects (810-814) within the area, as well as information that can be provided by other magnetic navigation devices. By introducing distortion into the GMF, these objects 810-814 may affect the magnetic reading values. Thus, the regional server can use various correlation methods as described above to combine the magnetic measurement values received from different magnetic navigation devices and generate updated geomagnetic map information such as geomagnetic map patches or multiple patches 820 (but not limited to these) transmitted to the main server 822. In certain embodiments, the main server 822 can generate a further geomagnetic map layer with a higher resolution than the EMAG data 824 by combining the EMAG data 824 with the geomagnetic map patch data. As shown in FIG. 8, many embodiments enable data to be transmitted in both directions. In other words, many embodiments can utilize the system architecture to generate geomagnetic map data 826 and provide the updated geomagnetic map data 826 to end devices (804-808) within the area. Different server systems can be used to receive magnetic measurement values, process the magnetic measurement values into updated geomagnetic information, and supply the geomagnetic map information to the magnetic navigation devices.

[0046] FIG. 9 shows an exemplary process for updating exemplary geomagnetic map information, in which a plurality of magnetic navigation devices are used to generate a geomagnetic map having a resolution higher than a baseline set of geomagnetic map information. In the illustrated embodiment, some magnetic navigation devices (1-n) generate magnetic measurement information based on the presence of those devices within a given area (902-906). Each regional server can then receive or share magnetic measurement information among the servers (908-912). Once the magnetic measurement information is compiled, it can be merged (914) and used to generate a geomagnetic map patch 916 having a resolution greater than the resolution of the reference data set of geomagnetic information. The geomagnetic map patch is then transmitted (918) and can be used to update the global geomagnetic map (920). In certain embodiments, the method shown in FIG. 9 can be used for any number of regional servers.

[0047] In certain embodiments, a magnetic navigation device can generate, transmit, and receive magnetic measurement information that can be formatted into one of several different data formats. FIG. 10 shows various processes executed within a magnetic navigation system where a magnetic navigation device 1002 can communicate with a regional server 1004. In certain embodiments, the magnetic navigation device 1002 can generate magnetic measurement information 1006 based on the region in which the magnetic navigation device 1002 is located and the applicable hardware that the magnetic navigation device 1002 has on board for generating data. The magnetic measurement information can then be transmitted to the regional server 1004 via a wireless connection (1008). As seen in FIGS. 1A - 1B and FIGS. 12 - 13, the wireless connection between the magnetic navigation device and the server system within the magnetic navigation system can include wireless communication via a cellular data network, a satellite communication link, a wireless access point, or other wireless communication channels (but not limited to these). The magnetic navigation device can also request geomagnetic map data 1010 (e.g., geomagnetic map tiles) for a given geographic region where the device is located. The regional server 1004 can transmit current regional geomagnetic map data 1012 to the magnetic navigation device based on the request. As described above, the geomagnetic data can be provided in combination with UI map tiles. In certain embodiments, the UI map tiles can be obtained from other servers.

[0048] The method by which magnetic measurement values can be created by a magnetic measurement device may depend on the availability of other sources of location information or the available network connection. FIG. 11 shows various magnetic measurement modes that can be used by a magnetic navigation device in a particular embodiment. The magnetic measurement values can be obtained using a magnetometer within the magnetic navigation device (1102). Magnetic measurement information can be generated by utilizing the magnetic measurement values (1104), and this information is transmitted to a server (e.g., a local server) within the magnetic navigation system (1105). The particular magnetic measurement information provided may depend on the availability of further sources of location information. For example, based on the available information, an operating mode such as a normal mode 1107, a network denial mode 1108, a blind mode 1110, or a GNSS denial mode 1112 can be selected or determined (1106). If reliable location information is available and the magnetic navigation device can access a wireless data network, the magnetic navigation device can operate in a standard or normal operating mode 1107, in which magnetic measurement values are collected and, when data is obtained, a combination of the magnetic measurement values and location information is transmitted to the magnetic navigation system (1105). However, if the device does not have an appropriate network signal 1108, if the network connection is established in the network denial mode 1108, data can be collected and stored locally for transmission. Similarly, the device can operate in the GNSS denial mode 1112, in which the device has an inappropriate GNSS signal 1110. In some embodiments, if a reliable GNSS signal is not available, the device can collect rough data using INS. Then, when the GNSS signal becomes available, the magnetic navigation device can start transitioning between collection modes or update the location estimate determined using INS or other location information sources. In a particular embodiment, the device can collect data using INS along with a good network signal and transmit it to a local server.In embodiments where there is no network signal, once an appropriate signal becomes available, data can be transferred to the local server.

[0049] FIG. 12 shows a decision-making process 1200 implemented within a magnetic navigation device to determine how to collect and transmit magnetic measurement information based on the availability of GNSS or a communication network. The magnetic navigation device can determine whether there is an appropriate GNSS signal (1202). If not, the magnetic navigation device can generate positioning data using INS positioning and dead reckoning (1204). Subsequently, the INS positioning data can be locally stored on device 1205 for transmission when a sufficient network signal is obtained. Subsequently, the system or device can determine whether there is a network signal 1206 sufficient to transmit the magnetic measurement information including the positioning data. If so, the data can be transmitted to the magnetic navigation system server (1208). If not, the magnetic measurement information can be stored until a network signal becomes available (1210).

[0050] Although a specific process for generating magnetic measurement information using different sources of positioning information has been described above, the magnetic navigation device can utilize any of various processes or sources for magnetic or positioning information during the generation of magnetic measurement information, depending on the requirements of a specific application in a particular embodiment.

[0051] As described above, the geomagnetic map can be used for any number of applications for navigation, including on land, in the air, and on water. A magnetic navigation device can utilize the geomagnetic map or further information regarding the magnetic susceptibility and conductivity of environmental substances to perform magnetic navigation. The specific way in which the magnetic navigation device navigates may depend on the availability of position - specifying information or other sources of network connection. When available, the magnetic navigation device can utilize GNSS to provide position - specifying information that can be improved in combination with magnetic measurements or INS measurements. When not available, the magnetic navigation device may rely on previous GNSS position - specifying information combined with INS measurements and magnetic measurements. As described above, the magnetic navigation device utilizes magnetic measurements to provide position - specifying information based on geomagnetic map information. The magnetic navigation device can store the geomagnetic map information. However, the magnetic navigation system in certain embodiments periodically updates the geomagnetic map information. Accordingly, the magnetic navigation device in certain embodiments can attempt to retrieve the updated geomagnetic map information to perform position - specifying or navigation based on magnetic measurements. As described above, GNSS information may be unreliable or unavailable in certain areas due to the surrounding environment (e.g., tall buildings, canyons, etc.). In certain embodiments, the geomagnetic map can include information regarding the reliability of GNSS position - specifying information at a particular location and information regarding the likelihood that the position is correct based on magnetic field measurements, in order to enable the magnetic navigation device to better adjust for discrepancies between positions determined based on GNSS information. The magnetic field measurements can utilize any of a variety of different methods to perform position - specifying in combination with additional sources of position - specifying information, depending on the requirements of a particular application in certain embodiments.

[0052] As previously described with respect to the generation of mapping data, certain embodiments can incorporate similar navigation operation modes. For example, if the navigation device has a reliable GNSS connection and a reliable cellular network connection, the navigation device may operate in a standard transmission mode (e.g., normal mode 1107) by receiving updated magnetic mapping tiles or cubes for a given operating area. Further, when the magnetic mapping tiles or cubes are transmitted to the navigation device, the device can compare the magnetic mapping tile / cube data with that of conventional GNSS data and evaluate the comparison for any divergences that can be transmitted to a regional server for later processing. Alternatively, if the device has an inadequate GNSS connection but has a sufficient network connection (e.g., GNSS denial mode 1112), many embodiments may rely primarily on geomagnetic map information including mapping tiles or cubes supplied from a regional server for navigation purposes. Also, certain embodiments may also incorporate the use of dead reckoning and INS to enhance the magnetic mapping data for reliable navigation.

[0053] Conversely, in some situations, it may not be possible to fully use GNSS or network connectivity to navigate using magnetic mapping data. Various embodiments can enable continuous navigation even when using an inappropriate cellular network signal to retrieve updated magnetic mapping data. For example, in the absence of a reliable cellular network connection and with only a GNSS connection available (e.g., network rejection mode 1108), some embodiments can continue to operate using magnetic mapping data previously transmitted and augmented with current GNSS data. Additionally, INS can be used to generate additional data for dead reckoning. Thus, INS, GNSS, and previously downloaded magnetic mapping data can be compared for irregularities that can later be transmitted to a local server for use in further improving the overall magnetic mapping data. Similarly, when some navigation devices are operating effectively in blind mode 1110 without a reliable GNSS or cellular network connection, INS and previously downloaded magnetic mapping data can be used for navigation purposes. INS and magnetic data are organically related to the navigation device and can also be used for later transmission to a local server for use in improving the overall magnetic map of a given area.

[0054] Figure 13 illustrates an exemplary method for navigating based on available location and network connectivity. In method 1300, a magnetic navigation device can determine that a suitable GNSS signal is available (1302) and proceed to obtain location information and request any available updated geomagnetic map information. If a GNSS signal is not available, the magnetic navigation device can estimate a location combined with magnetic measurements using measurements created by an IMU or other location information source (1304).

[0055] When a magnetic navigation device attempts to retrieve updated geomagnetic information, the magnetic navigation device can determine whether a network connection is available (1306). If a network connection is available, the magnetic navigation device can request and (when available) obtain updated geomagnetic map information. In certain embodiments, the geomagnetic map information for a particular region is provided in the form of geomagnetic map tiles (1308). The geomagnetic map information can be provided in any of a variety of formats, depending on the requirements of a particular application in a particular embodiment. If a network connection is not available, positioning or navigation can proceed using pre-cached geomagnetic map information (e.g., geomagnetic map tiles) (1310). In various embodiments, magnetic measurements can be processed using geomagnetic map information to perform positioning and compared to position estimates generated using any combination of GNSS, INS, or other sources of positioning data. The comparison can be evaluated for divergence and then further refined. In certain embodiments, the geomagnetic map information may include an indication of areas where GNSS signals are unreliable and may produce incorrect position estimates. Thus, the geomagnetic map information can be useful in resolving divergence. Also, the magnetic navigation device can use such information to process INS data to perform dead reckoning based on previously reliable GNSS information (potentially ignoring more recent but less reliable GNSS information).

[0056] If there is not a network connection sufficient to obtain geomagnetic map information, the magnetic navigation device can perform location identification or mapping in a conventional manner using GNSS information. However, the magnetic navigation device can continue to create magnetic measurements and can provide magnetic measurement information based on these measurements and location identification information derived from sources including GNSS information to the magnetic navigation system for the purpose of updating the Earth's geomagnetic map. In some embodiments, the geomagnetic map information can be downloaded later, and by using this information to determine location identification information together with GNSS data, the most accurate location information can be determined for use within the magnetic measurement information provided to the magnetic navigation system by the magnetic navigation device.

[0057] In certain embodiments, as described above, navigation technology can be performed regardless of the location of the device within the region. For example, in conventional GNSS systems, local anomalies can act as blockers of signals to the device. However, many embodiments take into account the magnetic susceptibility and conductivity of local anomalies, and since the system is based on stable magnetic mapping data, many embodiments can function both within and around local anomalies. This applies to indoor navigation in buildings. In some embodiments, the system can provide navigation tools for accurately navigating within a building as well as around the building. Further, as the landscape of the building can be mapped more accurately, the system is used more often within and around local anomalies.

[0058] In certain embodiments, navigation techniques similar to those described above can be extended by using contour lines for navigation on rough mapping data. A contour line can be referred to as a line of equal value of a magnetic field or magnetic field gradient on a map. In certain embodiments, the navigation technique can use the contour line to control an object by utilizing an error of a deviation value from a contour line or a set of contour lines related to a navigation device (similar to controlling an aircraft by position lines from wireless beacons).

[0059] Magnetic mapping data can be used in various systems and methods in the specific embodiments described herein. For example, some embodiments may be designed for search and rescue, or emergency response missions, so that a searcher can utilize magnetic mapping data not only from their own device but also data from a person in need of assistance to map the best course of action for performing position triangulation and rescue. Other embodiments can be used to extend existing navigation applications to aid in improving navigation through tunnels or underground passages. For example, mining operations can benefit from an improved magnetic mapping system for improved operator safety by reliable positioning. Further, many embodiments can be used for improved navigation and device positioning within buildings. For example, the systems and methods described herein can be used to assist device users when navigating buildings such as apartment complexes, enterprises, or factories. In some embodiments, the system can construct a magnetic map and magnetic mapping data for such positioning using Gaussian process regression (GPR) that can obviate the need for accurate floor measurements in such close positioning. FIGS. 14A - 14D illustrate exemplary magnetic data for improved positioning and show overlapping input and predicted data sets from which an extrapolated magnetic map for positioning can be generated. In particular, charts 1402 - 1416 shown in FIGS. 14A - 14D illustrate the visualization of the magnetic field, with different magnetic field strengths represented by different colors. The X - axis and Y - axis in these charts are the reference directions of some coordinate system in meters (e.g., ENU coordinate system). In the first chart 1402, the input data are magnetic values measured along a random trajectory where the positioning in the XY - axis is known. As can be seen from the first chart 1402, only 1 / 6 of the area is covered by the measured values. Chart 1404 shows the same trajectory with respect to the latitude - longitude axis. Charts 1406 - 1416 represent the process of filling map patches with magnetic fields that interpolate between different combinations of empty regions.In particular, chart 1408 represents the visualization of a magnetic field with a reliable position - specifying radius and without interpolation; chart 1410 shows the filling of the entire patch based on GPR and without a radius; chart 1412 represents the visualization of magnetism filled from both GPR interpolation and actual input data; chart 1414 shows the filling of the entire patch based on GPR taking into account a reliable position - specifying radius; and finally, chart 1416 represents the visualization of magnetism filled from both GPR interpolation and actual input data taking into account a reliable position - specifying radius. Similar embodiments can be incorporated for use with autonomous robots or drones that can be used in several different situations.

[0060] Other embodiments of a magnetic mapping or navigation system can be used in a number of outdoor environments including, but not limited to, GNSS - deprived environments. For example, various embodiments may incorporate a trace - back function. Such a function can be useful for a robot or a remotely - controlled device navigating to a particular location. If the device loses line - of - sight with the control unit, the device can utilize stored or previously - used magnetic mapping data to return to the control unit along a path without the need for line - of - sight or a reliable GNSS or network connection. Similarly, many such embodiments can be used in various applications where GNSS or network connections are restricted. For example, as described above, embodiments can be used to extend other mapping applications to enable reliable localization in remote or other locations with poor connectivity. For example, FIG. 15 shows a set of magnetic mapping data 1502 for a given device along a given trajectory 1504 on the first day (e.g., May 11, 2020) and the second day (e.g., May 14, 2020). Specifically, FIG. 15 shows that magnetic measurements made on different days or times are reproducible for navigation and mapping purposes. In certain embodiments, stored data can be used and reused to enable continuous and reliable localization when connections may be interrupted.

[0061] Other embodiments can be incorporated on a smaller scale for a variety of different uses. For example, an individual may define a given area as the “desired area” of operation. The desired area of operation can be established using a geomagnetic fencing element to “enclose” known devices within the desired area or to exclude them from the desired area. Some examples include dog collars that can be used on specific land parcels or within specific areas of a city. In some embodiments, a dog collar or location device can be designed to prevent movement beyond a defined area or to prevent functionality beyond a defined area. Other examples may include a protected area where, as an example, a portable device may pose an excessive risk. Further, the alerts can be used to notify other devices of movement within, near, and beyond the desired area.

[0062] Many of the systems and methods described herein may also be useful in areas that are subject to a high level of interference with various anomalies or reduced connectivity. For example, many marine vessels, particularly submarines, may require a more reliable location system. Thus, a magnetic mapping and navigation system can be used in certain embodiments on submarines, such as military or scientific exploration vessels. Further, many such devices may utilize secondary operating devices, such as remotely operated devices or projectiles, that may similarly require reliable location for guidance. Accordingly, the above embodiments can be adapted for use in devices such as primary location or extended location systems.

[0063] Considering the reliability of the embodiments of the magnetic mapping and location system described herein, many other applications can be understood. For example, since many embodiments can operate without a proper GNSS or network connection, some systems may be adapted to a leader / follower configuration. The leader may be a device that passes through a specific area (dead zone) where connectivity may be poor. During movement, the leader device generates magnetic mapping data that can be used to generate a trajectory and rough mapping data. Such data is then transmitted to the follower device before entering the dead zone, and the follower device can then utilize the data from the leader device to successfully navigate the dead zone. Further, each follower device can generate follower data to be transmitted that can be used to improve the magnetic mapping tiles that can be transmitted to other follower devices.

[0064] Furthermore, as previously described with regard to extrapolating various two-dimensional data sets to generate a three-dimensional data set, some systems can be adapted for use in ground-to-air location technology. For example, a ground device can be used to generate magnetic mapping data, and the magnetic mapping data can then be extrapolated upward to generate a three-dimensional mapping cube. The three-dimensional mapping cube will then contain altitude data, and the altitude data can be used by an air device for air location / navigation through a specific area.

[0065] The concepts herein can be implemented in particularly various configurations. For example, a navigation system in which a continuously updated magnetic mapping system compares individual area device profiles to generate new mapping tiles and a method for using this navigation system. According to an embodiment, achieving such functionality requires the implementation of a special arrangement or design between the above-described subsystems and their equivalents.

[0066] FIG. 16 shows an exemplary computer system 1600. In certain embodiments, one or more computer systems 1600 perform one or more steps of one or more of the methods described or illustrated herein. In certain embodiments, computer system 1600 may be a computing system or device associated with magnetic navigation device 110, regional data server 112, or main mapping server 116. In certain embodiments, one or more computer systems 1600 provide the functionality described or illustrated herein. In certain embodiments, software executed on one or more computer systems 1600 performs one or more steps of one or more of the methods described or illustrated herein, or provides the functionality described or illustrated herein. Certain embodiments include one or more portions of one or more computer systems 1600. As used herein, references to a computer system may, where appropriate, include a computing device, and vice versa. Further, where appropriate, references to a computer system may also include one or more computer systems.

[0067] The present disclosure contemplates any suitable number of computer systems 1600. The present disclosure contemplates computer systems 1600 in any suitable physical form. By way of example and not limitation, computer system 1600 may be an embedded computer system, a system-on-chip (SOC), a single-board computer system (SBC) (such as, for example, a computer-on-module (COM) or system-on-module (SOM), etc.), a desktop computer system, a laptop or notebook computer system, an interactive kiosk, a mainframe, a mesh of computer systems, a cellular phone, a personal digital assistant (PDA), a server, a tablet computer system, an augmented / virtual reality device, or a combination of two or more of these. Optionally, computer system 1600 may include one or more computer systems 1600, may be of a single type or distributed, may span multiple locations, may span multiple machines, may span multiple data centers, or may exist within a cloud that can include one or more cloud components within one or more networks. Optionally, one or more computer systems 1600 may perform one or more steps of one or more of the methods described or illustrated herein without substantial spatial or temporal limitation. By way of example and not limitation, one or more computer systems 1600 may perform one or more steps of one or more of the methods described or illustrated herein in real time or in batch mode. Optionally, one or more computer systems 1600 may perform one or more steps of one or more of the methods described or illustrated herein at different times or at different locations.

[0068] In certain embodiments, computer system 1600 includes processor 1602, memory 1604, storage 1606, input / output (I / O) interface 1608, communication interface 1610, and bus 1612. Although the present disclosure describes and illustrates a particular computer system having a particular number of particular components in a particular configuration, the present disclosure contemplates any suitable computer system having any suitable number of any suitable components in any suitable configuration.

[0069] In certain embodiments, processor 1602 includes hardware for executing instructions, such as instructions that make up a computer program. By way of example and not limitation, to execute instructions, processor 1602 may read (or fetch) instructions from internal registers, internal cache, memory 1604, or storage 1606, decode them, execute them, and then write one or more results to internal registers, internal cache, memory 1604, or storage 1606. In certain embodiments, processor 1602 may include one or more internal caches for data, instructions, or addresses. The present disclosure contemplates processor 1602 including any suitable number of any suitable internal caches, as necessary. By way of example and not limitation, processor 1602 may include one or more instruction caches, one or more data caches, and one or more translation lookaside buffers (TLBs). Instructions in the instruction cache may be copies of instructions in memory 1604 or storage 1606, and the instruction cache may speed up retrieval of those instructions by processor 1602. Data in the data cache may be copies of data in memory 1604 or storage 1606 for use by instructions executed by processor 1602, results of previous instructions executed by processor 1602 for access by subsequent instructions executed by processor 1602 or for writing to memory 1604 or storage 1606, or other suitable data. The data cache may speed up read or write operations by processor 1602. The TLB may speed up virtual address translation for processor 1602. In certain embodiments, processor 1602 may include one or more internal registers for data, instructions, or addresses. The present disclosure contemplates processor 1602 including any suitable number of any suitable internal registers, as necessary. Optionally, processor 1602 may include one or more arithmetic logic units (ALUs), may be a multi-core processor, or may include one or more processors 1602.Although the present disclosure describes and illustrates a particular processor, the present disclosure contemplates any suitable processor.

[0070] In certain embodiments, memory 1604 includes a main memory for storing instructions for execution by processor 1602 or data for operation of processor 1602. By way of example and not limitation, computer system 1600 may load instructions into memory 1604 from storage 1606 or another source (e.g., another computer system 1600, etc.). Processor 1602 may then load instructions from memory 1604 into internal registers or an internal cache. To execute the instructions, processor 1602 may fetch the instructions from the internal registers or internal cache and decode them. During or after execution of the instructions, processor 1602 may write one or more results (which may be intermediate or final results) to the internal registers or internal cache. Processor 1602 may then write one or more of those results to memory 1604. In certain embodiments, processor 1602 executes only instructions within one or more internal registers or internal cache or in memory 1604 (as opposed to storage 1606 or others) and operates only on data within one or more internal registers or internal cache or in memory 1604 (as opposed to storage 1606 or others). One or more memory buses (which may each include an address bus and a data bus) may connect processor 1602 to memory 1604. Bus 1612 may include one or more memory buses, as described below. In certain embodiments, one or more memory management units (MMUs) exist between processor 1602 and memory 1604 and facilitate access to memory 1604 requested by processor 1602. In certain embodiments, memory 1604 includes random access memory (RAM). This RAM may be volatile memory, if desired. Optionally, this RAM may be dynamic RAM (DRAM) or static RAM (SRAM). Further, optionally, this RAM may be single-port or multi-port RAM. The present disclosure contemplates any suitable RAM. Memory 1604 may optionally include one or more memories 1604.Although the present disclosure describes and illustrates particular memories, the present disclosure contemplates any suitable memory.

[0071] In certain embodiments, storage 1606 includes mass storage for data or instructions. By way of example and not limitation, storage 1606 may include a hard disk drive (HDD), a floppy (registered trademark) disk drive, flash memory, an optical disk, a magneto-optical disk, magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of these. Storage 1606 may include removable or non-removable (or fixed) media, as desired. Storage 1606 may be internal or external to computer system 1600, as desired. In certain embodiments, storage 1606 is non-volatile solid state memory. In certain embodiments, storage 1606 includes read only memory (ROM). Optionally, this ROM may be mask programmed ROM, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM) or flash memory, or a combination of two or more of these. The present disclosure contemplates mass storage 1606 in any suitable physical form. Storage 1606 may include one or more storage control units, as desired, to facilitate communication between processor 1602 and storage 1606. Optionally, storage 1606 may include one or more storage 1606. Although the present disclosure describes and illustrates particular storage, the present disclosure contemplates any suitable storage.

[0072] In certain embodiments, I / O interface 1608 includes hardware, software, or both that provide one or more interfaces for communication between computer system 1600 and one or more I / O devices. Computer system 1600 may optionally include one or more of these I / O devices. One or more of these I / O devices may enable communication between a person and computer system 1600. By way of non-limiting example, the I / O devices include a keyboard, keypad, microphone, monitor, mouse, printer, scanner, speaker, still camera, stylus, tablet, touch screen, trackball, video camera, another suitable I / O device, or a combination of two or more of these. The I / O devices may include one or more sensors. The present disclosure contemplates any suitable I / O devices and any suitable I / O interface 1608 therefor. Optionally, I / O interface 1608 may include one or more devices or software drivers that enable processor 1602 to drive one or more of these I / O devices. I / O interface 1608 may optionally include one or more I / O interfaces 1608. Although the present disclosure describes and illustrates particular I / O interfaces, the present disclosure contemplates any suitable I / O interface.

[0073] In certain embodiments, communication interface 1610 includes one or more interfaces for communication (e.g., packet-based communication, etc.) between computer system 1600 and one or more other computer systems 1600 or one or more networks, including hardware, software, or both. By way of non-limiting example, communication interface 1610 may include a network interface controller (NIC) or network adapter for communicating with Ethernet® or other wired-based networks, or a wireless NIC (WNIC) or wireless adapter for communicating with wireless networks such as WI-FI® networks. The present disclosure contemplates any suitable network and any suitable communication interface 1610 for such network. By way of non-limiting example, computer system 1600 may communicate with one or more portions of an ad hoc network, a personal area network (PAN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), or the Internet, or a combination of two or more of these. One or more portions of these networks may be wired or wireless. As an example, computer system 1600 may communicate with a wireless PAN (WPAN) (e.g., BLUETOOTH® WPAN, etc.), a WI-FI network, a WI-MAX network, a cellular phone network (e.g., a global system for mobile communications (GSM) network for mobile communications, etc.), or other suitable wireless networks, or a combination of two or more of these. Computer system 1600 may include any suitable communication interface 1610 for any of these networks, as needed. Communication interface 1610 may include one or more communication interfaces 1610, as needed. The present disclosure describes and illustrates particular communication interfaces, but the present disclosure contemplates any suitable communication interface.

[0074] In certain embodiments, bus 1612 includes hardware, software, or both that connect components of computer system 1600 to each other. By way of example and not limitation, bus 1612 may include an Accelerated Graphics Port (AGP) or other graphics bus, an Extended Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a HYPERTRANSPORT (HT) interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBAND interconnect, a Low Pin Count (LPC) bus, a memory bus, a MicroChannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCIe) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or another suitable bus, or a combination of two or more of these. Bus 1612 may include one or more buses 1612 as needed. Although the present disclosure describes and illustrates particular buses, the present disclosure contemplates any suitable bus or interconnect.

[0075] As used herein, a computer-readable non-transitory storage medium or media may include, as needed, one or more semiconductor-based or other integrated circuits (ICs) (e.g., a Field Programmable Gate Array (FPGA) or an Application Specific IC (ASIC), etc.), a hard disk drive (HDD), a hybrid hard drive (HHD), an optical disk, an optical disk drive (ODD), a magneto-optical disk, a magneto-optical drive, a floppy (registered trademark) disk drive, a floppy (registered trademark) disk drive (FDD), magnetic tape, a solid state drive (SSD), a RAM drive, a SECURE DIGITAL card or drive, any other suitable computer-readable non-transitory storage medium, or any suitable combination of two or more of these. The computer-readable non-transitory storage medium may be, as needed, volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory.

[0076] In this specification, "or" is inclusive and not exclusive, unless explicitly stated otherwise or unless the context dictates otherwise. Thus, in this specification, "A or B" means "A, B, or both", unless explicitly stated otherwise or unless the context dictates otherwise. Further, "and" is both joint and several, unless explicitly stated otherwise or unless the context dictates otherwise. Thus, in this specification, "A and B" means "A and B together or separately", unless explicitly stated otherwise or unless the context dictates otherwise.

[0077] The scope of the present disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the exemplary embodiments described or illustrated herein that would be understood by those skilled in the art. The scope of the present disclosure is not limited to the exemplary embodiments described or illustrated herein. Further, although the present disclosure describes and illustrates each of the embodiments herein as including a particular component, element, feature, function, operation, or step, any of these embodiments may include any combination or permutation of any of the components, elements, features, functions, operations, or steps described or illustrated anywhere herein that would be understood by those skilled in the art. Additionally, references in the appended claims to a component of an apparatus or system, or an apparatus or system adapted, arranged, capable, configured, enabled, operable, or operative to perform a particular function include that apparatus, system, or component as long as that apparatus, system, or component is so adapted, configured, capable, constructed, enabled, operable, or operative, regardless of whether or not that particular function is activated, turned on, or unlocked. Further, the scope of the present disclosure encompasses all advantages of the exemplary embodiments described or illustrated herein that would be understood by those skilled in the art. The scope of the present disclosure is not limited to the specific advantages specifically described or illustrated herein.

Claims

1. Receiving magnetic measurements of one or more geographic regions collected over a period of time from a plurality of magnetic navigation devices; Performing a similarity correlation analysis on the magnetic measurements of the one or more geographic regions collected over the period; Generating one or more geomagnetic map patches corresponding to the one or more geographic regions based on the performance of the similarity correlation analysis; Transmitting the one or more geomagnetic map patches to a main mapping server to update geomagnetic map data; Receiving updated geomagnetic map data from the main mapping server; and Transmitting the updated geomagnetic map data to the plurality of magnetic navigation devices for navigation and location determination. A method comprising the above steps.

2. The method according to claim 1, wherein the step of performing the similarity correlation analysis comprises: Comparing the first magnetic measurements of a first magnetic navigation device with the second magnetic measurements of at least one second magnetic navigation device for each geographic region of the one or more geographic regions; Determining overlapping magnetic measurements between the first magnetic measurements and the second magnetic measurements over the period; and Identifying the similarity between the overlapping magnetic measurements. A method comprising the above steps.

3. The method according to claim 1, further comprising: Generating a probabilistic magnetic gradient map based on the similarity between the magnetic measurements collected over the period.

4. The method according to claim 3, wherein the probabilistic magnetic gradient map is used to update the geomagnetic map data.

5. The method according to claim 1, further comprising: Assigning a confidence factor to each of the plurality of magnetic navigation devices based on the reliability and accuracy of the hardware of the magnetic navigation devices; and Weighting the magnetic measurements of the plurality of magnetic navigation devices according to the assigned confidence factors. A method comprising the above steps.

6. The method according to claim 5, wherein the similarity correlation analysis is performed based on the weighted magnetic measurements of the plurality of magnetic navigation devices.

7. The method according to claim 1, wherein the geomagnetic map data includes a global geomagnetic map.

8. The method according to claim 1, wherein a magnetic navigation device uses the updated geomagnetic map data to perform navigation in an area where the reliability of a global navigation satellite system (GNSS) signal is low or insufficient.

9. One or more computer-readable non-transitory storage media embodying software, which, when executed, receives magnetic measurements of one or more geographic regions collected over a period of time from a plurality of magnetic navigation devices, performs a similarity correlation analysis on the magnetic measurements of the one or more geographic regions collected over the period, generates one or more geomagnetic map patches corresponding to the one or more geographic regions based on the performance of the similarity correlation analysis, transmits the one or more geomagnetic map patches to a main mapping server to update geomagnetic map data, receives updated geomagnetic map data from the main mapping server, and is operable to transmit the updated geomagnetic map data to the plurality of magnetic navigation devices for navigation and positioning. A medium.

10. The medium according to claim 9, wherein, to perform the similarity correlation analysis, the software, when executed, compares first magnetic measurements of a first magnetic navigation device with second magnetic measurements of at least one second magnetic navigation device for each geographic region of the one or more geographic regions, determines overlapping magnetic measurements between the first magnetic measurements and the second magnetic measurements over the period, and is operable to identify a similarity between the overlapping magnetic measurements. A medium.

11. The medium according to claim 9, wherein the software, when executed, is operable to generate a probabilistic magnetic gradient map based on a similarity between the magnetic measurements collected over the period.

12. The medium according to claim 11, wherein the probabilistic magnetic gradient map is used to update the geomagnetic map data.

13. The medium according to claim 9, wherein the software, when executed, Based on the reliability and accuracy of the hardware of the magnetic navigation device, assign a reliability coefficient to each of the plurality of magnetic navigation devices, and also operable to weight the magnetic measurement values of the plurality of magnetic navigation devices according to the assigned reliability coefficients, medium.

14. The medium according to claim 13, wherein the similarity correlation analysis is performed based on the weighted magnetic measurement values of the plurality of magnetic navigation devices.

15. One or more processors, and one or more computer-readable non-transitory storage media connected to and including instructions for one or more of the processors, A system comprising: when the instructions are executed by one or more of the processors, the system is caused to receive magnetic measurement values of one or more geographic regions collected over a period of time from a plurality of magnetic navigation devices, perform a similarity correlation analysis on the magnetic measurement values of the one or more geographic regions collected over the period, generate one or more geomagnetic map patches corresponding to the one or more geographic regions based on the execution of the similarity correlation analysis, send the one or more geomagnetic map patches to a main mapping server to update geomagnetic map data, receive updated geomagnetic map data from the main mapping server, and also send the updated geomagnetic map data to the plurality of magnetic navigation devices for navigation and location determination. system operable to

16. The system according to claim 15, wherein, to perform the similarity correlation analysis, when the one or more processors execute the instructions, the system is caused to compare the first magnetic measurement value of the first magnetic navigation device with the second magnetic measurement value of at least one second magnetic navigation device for each geographic region of the one or more geographic regions, determine overlapping magnetic measurement values between the first magnetic measurement value and the second magnetic measurement value over the period, and also identify the similarity between the overlapping magnetic measurement values. system operable to

17. The system according to claim 15, wherein when the one or more processors execute the instructions, the system is operable to generate a probabilistic magnetic gradient map based on the similarity between the magnetic measurements collected over the period.

18. The system according to claim 17, wherein the probabilistic magnetic gradient map is used to update the geomagnetic map data.

19. The system according to claim 15, wherein when the one or more processors execute the instructions, the system is caused to assign a confidence factor to each of the plurality of magnetic navigation devices based on the reliability and accuracy of the hardware of the magnetic navigation devices, and weight the magnetic measurements of the plurality of magnetic navigation devices according to the assigned confidence factors. The system is operable to do so.

20. The system according to claim 19, wherein the similarity correlation analysis is performed based on the weighted magnetic measurements of the plurality of magnetic navigation devices.

21. Means for receiving magnetic measurements of one or more geographic regions collected over a period from a plurality of magnetic navigation devices; Means for performing a similarity correlation analysis on the magnetic measurements of one or more geographic regions collected over the period; Means for generating one or more geomagnetic map patches corresponding to the one or more geographic regions based on the execution of the similarity correlation analysis; Means for transmitting the one or more geomagnetic map patches to a main mapping server to update geomagnetic map data; Means for receiving updated geomagnetic map data from the main mapping server; and Means for transmitting the updated geomagnetic map data to the plurality of magnetic navigation devices for navigation and positioning. A system comprising.

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